This project aims to determine post-prandial nutrient metabolism in males and females in the fed and fasted condition. To achieve this aim subjects consume a liquid meal containing isotopically labeled lipid (1-14C oleic acid) and carbohydrate (U-13C glucose) to follow the partitioning of meal derived nutrients. Baseline measurements are made prior to consumption of the meal and post-prandial metabolism is followed acutely for 6 hours. The leg limb balance technique is used to determine skeletal muscle metabolism while a constant infusion of 2H2 glucose to measure endogenous glucose production. Indirect calorimetry is used to determine wholebody nutrient oxidation and energy expenditure with breath samples being collected separately for measurement of 14CO2 and 13CO2 content. Muscle and fat biopsies are taken pre-meal and at the end of the 6 hours. Limb balance measures are ended at the 6 hour time point but further blood and breath samples are collected at 9, 11, and 21 hours post meal. It is hypothesized that a) in the fed condition, more meal derived lipid will be stored vs oxidized, with the converse being true for the meal derived glucose and b) females will oxidize more of the meal derived glucose, compared to males, particularly in the fed condition. Thus females will direct more meal derived lipid to storage. This study will provide important data on the interaction between post-prandial lipid and carbohydrate metabolism, in males and females.